1. Field of the Invention
The present invention relates generally to a dynamometer and more specifically to a twin roller type chassis dynamometer.
2. Description of the Prior Art
Twin roller type chassis dynamometers are usually of the type wherein the vehicle is driven onto the same and used for a wide variety of purposes such as determining exhaust gas emission characteristics, fuel consumption and the like.
However, in order to be able to provide satisfactory simulation characteristics it is necessary the device be able to produce running resistance, variable load, and the like.
In order to vary the load, a twin roller type chassis dynamometer of the type shown in FIG. 2 has been used. In this illustrated arrangement, in view of space efficiency and cost requirements, the rollers are arranged to have a diameter of about 500 mm and the free roller is provided internally with a fly wheel which can rotate faster than the same.
As shown, this prior art twin roller type dynamometer includes a roller dynamometer 1, a load roller 2 and two free rollers 3 and 4. The roller dynamometer and the load roller 2 are connected by way of a coupling shaft 6 and brake 6 so as to undergo synchronous rotation. The two free rollers 3 and 4 are interconnected by way of coupling shaft 7 and brake 8 and are arranged to rotate synchronously. Roller dynamometer 1 and free roller 3 are arranged in parallel. Load roller 2 and free roller 4 are similarly arranged.
The chassis dynamometer is further provided with a clutch 9 which is operatively connected to an output shaft 10 of the load roller 2. The output shaft 11 of the free roller 4 is connected with the output shaft 10 by way of a timing belt 12.
Flywheels 13 and 14 are disposed within each of the free rollers 3 and 4. Each of these flywheels 13 and 14 are arranged so that they can rotate faster than the respective free rollers in which they are housed.
However, this arrangement has suffered from the drawback that, in order to render the overall arrangement compact, that the dynamometer device must be disposed within the roller dynamometer 1.
As a result, as the diameter of the roller dynamometer 1 is limited and the rotational speed of the load roller 2 cannot be varied, the amount by which the load can be varied is limited to a maximum of about 75 KW.
However, high speed large displacement engines currently tend to produce in the order of 220 KW. Therefore, the above type of twin roller type chassis dynamometer does not exhibit the capacity required for suitably testing vehicles fitted with such powerful large displacement engines.
In order to permit the capacity of the device to be increased, it is necessary to replace the existing dynamometer with a larger one. However, this requires an increased amount of space and increases the cost of the arrangement.